1. Field of the Invention
The present invention relates to an automatic clamping device for cableway systems, in particular for two-cable systems.
2. Discussion of the Background
For some years it has been general practice to manufacture cableway systems of the single-cable type, wherein the only cable present on the system can be driven in translation by means of a winch, and it serves both as a carrying cable and as a traction cable of the vehicles, in particular cable-cars, passing on the line.
Each telpher is supported upwards by a clamping vice of the cable, so that the vehicles can be supported and moved at the same time by the same cable.
Nevertheless, due to the mechanical stresses involved, the potentiality of the systems of this kind is limited to a relatively small number of passengers that every single vehicle can transport.
On the other hand, in a two-cable system the weight of the vehicle is not supported by the traction cable through the vice; on the contrary, besides the traction stresses, the vice also supports the stresses transmitted from the traction cable to the carrying cable and viceversa, which are due to the weight of the traction cable and to its deviation, in particular when passing on the line supports provided along the run, when the traction cable is lifted from the support rollers.
Those stresses can have relatively high values, and they are directed downwards.
Moreover, the stress transferred between the traction cable and carrying cable when passing on the line supports depends on the tension of the traction cable and on the entity of the lifting when passing on the rollers, and it easily reaches high values if the tension of the traction cable is considerable. As the tension cannot be reduced, it is indispensable to limit as much as possible the above lifting, and this implies particularly limiting geometrical bounds.
For the reasons mentioned above, also the provision of installing two vices, which must necessarily be mounted at the two sides of the suspension pin and at a considerable distance from it, for the purpose of not interfering with it, does not give any advantage, as it would imply lifting the cable from the rollers by an unacceptable entity.
Moreover, said arrangement would imply excessive overall dimensions of the structure.
Thus, object of the present invention is that of solving the technical disadvantages mentioned above, and in particular that of providing an automatic clamping device for cableway systems, which should exhibit particularly high clamping performances, with respect to the prior art, so as to allow the system to support high-capacity telphers, requiring at the same time a limited actuating force, as the opening lever arm is almost doubled with respect to the traditional devices currently used.
Another object of the present invention is that of providing an automatic clamping device for cableway systems, which should allow minimising the overall dimensions of the entire structure.
Last but not least, a further object of the present invention is that of providing an automatic clamping device for cableway systems, which should be particularly safe and reliable, and with relatively low price in virtue of the attained advantages.
These and other objects, according to the present invention, are attained by realising a novel automatic clamping device for cableway systems.
Advantageously, the presence of a single clamping device or vice according to the present invention, in a two-cable system, independently of the number of people transported by the telphers, allows limiting as much as possible the lifting of the cable when passing on the rollers; moreover, the open structure and the possibility of opening and closing the vice by directly operating on the mobile jaw, with consequent measure of the clamping moment directly onto said jaw, are qualifying technical features, above all from the point of view of the system safety.
Finally, it is necessary to install the jaw not too far from the suspension pin, but without interfering with it.
A peculiar feature of two-cable systems is that the jaw never comes into contact with the line rollers, since the traction cable is lifted by the jaw when passing on the rollers for the purpose of allowing transverse oscillations, which occur with respect to an axis arranged at the height of the traction cable: thus, side oscillations imply a transverse movement of the jaw with respect to the rollers, which would not be possible without a lifting; as a consequence, the shaping of the jaws is not bound by the configuration of the line rollers, and the jaws can exhibit the necessary stiffness without any space problems.
In addition, since the two-cable system with single carrying cable allows an easy rescue with a suspended system, which uses the traction cable as carrying cable for the rescue trolley, the jaws are configured so that they can be climbed over by said vehicle.
In conclusion, the vice is characterised by high technical performances; in fact, as the system must support 15-20 seat vehicles with a single vice, also giving up to climb high gradients, the vice must provide for a clamping in the range of about twice that provided by vices and systems of the same type currently in use.
On the other hand, advantageously, the driving force is in the same range of entity, as also the opening lever arm is almost doubled.